Broadcasting receiver and method for displaying 3D images

ABSTRACT

Disclosed are a method for displaying 3D images and a broadcast receiver. The method for displaying 3D images according to one embodiment of the present invention comprises the steps of: receiving broadcasting signals including video data and 3D object data; decoding the 3D object data, the 3D object data including texts or image information for a 3D object, output position information of the 3D object, and disparity information of the 3D object; obtaining parallax values from the disparity information and producing distortion compensation coefficients using the parallax values; adjusting a display size of the 3D object using the distortion compensation coefficients; and outputting and displaying the 3D object.

This application is a Continuation of U.S. application Ser. No.13/521,384, filed Jul. 10, 2012, which claims the benefit of priority ofPCT Application No. PCT/KR2011/000136 filed on Jan. 10, 2011 whichclaims the benefit of priority of U.S. Provisional Application No.61/294,090 filed on Jan. 11, 2010, all of which are incorporated byreference in their entirety herein.

TECHNICAL FIELD

The present invention relates to a broadcast receiver and a 3D imagedisplay method thereof, and more particularly, to a broadcast receiverfor displaying a 3D image included in a broadcast signal by adjusting adisplay effect of a 3D object and a 3D image display method thereof.

BACKGROUND ART

Generally, a 3-dimensional (3D) image (or stereoscopic image) provides astereoscopic effect using the stereoscopic visual principle of botheyes. Since human depth perception is based upon binocular parallaxcaused by a distance between the eyes of about 65 mm, the 3D imageenables both right and left eyes to respectively view associated planeimages, resulting in the stereoscopic effect and the perspective effect.

Such a method for displaying a 3D image may be classified into astereoscopic scheme, a volumetric scheme, a holographic scheme, etc. Incase of the stereoscopic scheme, a left view image to be viewed by theleft eye and a right view image to be viewed by the right eye areprovided so that the viewer's left eye views the left view image and theviewer's right eye views the right view image through polarized glassesor a display device, resulting in recognition of the 3D image effect.

DETAILED DESCRIPTION OF THE INVENTION Technical Problems

It is a technical object of the present invention to provide users withmore convenient and efficient 3D viewing environments by adjusting adisplay effect which may be generated when a broadcast receiver receivesand displays 3D image data.

Technical Solutions

To achieve the above technical object, a 3D image display methodaccording to one embodiment of the present invention includes receivinga broadcast signal including video data and 3D object data; decoding the3D object data, wherein the 3D object data includes text or imageinformation about a 3D object, output location information of the 3Dobject, and disparity information of the 3D object; acquiring a parallaxvalue from the disparity information and calculating a distortioncompensation factor using the parallax value; adjusting a display sizeof the 3D object using the distortion compensation factor; anddisplaying the 3D object.

To achieve the above technical object, a broadcast receiver according toone embodiment of the present invention includes a broadcast signalreceiver for receiving a broadcast signal including video data and 3Dobject data; a decoder for decoding the 3D object data, wherein the 3Dobject data includes text or image information about a 3D object, outputlocation information of the 3D object, and disparity information of the3D object; a graphics engine for acquiring a parallax value from thedisparity information, calculating a distortion compensation factorusing the parallax value, and adjusting a display size of the 3D objectusing the distortion compensation factor; and a formatter for displayingthe 3D object.

Advantageous Effects

According to the present invention, more convenient 3D image viewenvironments can be provided to users by solving a size distortionphenomenon of an image generated by a perspective effect in which a 3Dobject appears during display of the 3D object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a 3D object display method according toan embodiment of the present invention;

FIG. 2 is a diagram illustrating a 3D effect of 3D object displayaccording to an embodiment of the present invention;

FIG. 3 is a diagram illustrating 3D object display in accordance with adisparity value according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating an interval between a user, an image,and a screen during 3D image display according to an embodiment of thepresent invention;

FIG. 5 is a diagram illustrating a broadcast receiver according to anembodiment of the present invention;

FIG. 6 is a diagram illustrating a broadcast receiver according toanother embodiment of the present invention;

FIG. 7 is a flowchart illustrating a 3D object display method accordingto an embodiment of the present invention; and

FIG. 8 is a diagram illustrating a UI for adjusting the size of a 3Dobject according to an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The present invention should not be limited to the specificembodiments described herein.

Most terms disclosed in the present invention are defined inconsideration of functions of the present invention and correspond togeneral terms well known in the art and may vary according to intentionof those skilled in the art, usual practices, or introduction of newtechnologies. Some of the terms mentioned in the description of thepresent invention may have been selected by the applicant at his or herdiscretion, and in such cases the detailed meanings thereof will bedescribed in relevant parts of the description herein. Thus, the termsused in this specification should be interpreted based on thesubstantial meanings of the terms and the whole content of thisspecification rather than their simple names or meanings.

A 3D image display method includes a stereoscopic image display schemein which two viewpoints are considered and a multi-view image displayscheme in which three or more viewpoints are considered. In contrast, aconventional single view image scheme may be referred to as a monoscopicimage scheme.

The stereoscopic image display scheme uses one pair of right and leftimages acquired when a left-side camera and a right-side camera spacedapart from each other by a predetermined distance capture the sametarget object. The multi-view image display scheme uses three or moreimages captured by three or more cameras spaced apart by a predetermineddistance or angle. Although the following description disclosesembodiments of the present invention using the stereoscopic imagedisplay scheme as an example, the inventive concept of the presentinvention may also be applied to the multi-view image display scheme.

A stereoscopic image or multi-view image may be compressed and coded fortransmission according to a variety of methods including a MovingPicture Experts Group (MPEG) scheme.

For example, the stereoscopic image or multi-view image may becompressed and coded according to an H.264/Advanced Video Coding (AVC)scheme. In this case, a reception system may obtain a 3D image bydecoding a received image in reverse order of the H.264/AVC codingscheme.

In addition, one of a left view image and a right view image ofstereoscopic images or one of multiple-view images may be assigned as abase layer image and the remaining one may be assigned as an extendedlayer image. The base layer image may be encoded using the same schemeas a monoscopic imaging scheme. In the extended layer image, onlyinformation of the relationship between the base layer image and theextended layer image may be encoded and transmitted. In this case, thebase layer image may be referred to as a base view image and theextended layer image may be referred to as an extended view image. As anexemplary compression and coding scheme for the base layer image, JPEG,MPEG-2, MPEG-4, or H.264/AVC may be used. In one embodiment of thepresent invention, the H.264/AVC scheme is exemplarily used. Thecompression coding scheme for a higher layer image such as the extendedlayer image uses an H.264/Multi-view Video Coding (MVC) scheme in oneembodiment of the present invention.

If the MVC scheme is used in addition to the AVC scheme for the purposeof stereoscopic image display or if left/right image sequences are codedusing the AVC scheme alone, one consideration when it is desired tobroadcast 3D content is compatibility with an existing 2D broadcastreceiver. To this end, if one of left/right viewpoint images is codedusing a backward compatible method and then is transmitted for a legacybroadcast receiver which does not support 3D image display, the 2Dbroadcast receiver recognizes and generates only a signal correspondingto the backward compatible image so that a user can view content even inthe conventional receiver. Hereinafter, a base layer image of aviewpoint transmitted for the legacy broadcast receiver may be referredto as a base view image or a base view video and an extended layer imagetransmitted for 3D image display may be referred as to an extended viewimage or an extended view video.

If base view video data and extended view video data are transmitted,the legacy 2D broadcast receiver may display a 2D image based upon thebase view video data and the 3D broadcast receiver may display a 3Dimage based upon the base view video data and the extended view videodata. Nonetheless, a method for displaying image objects (e.g. subtitlesor captions) added to a main image becomes problematic.

Hereinafter, an additionally displayed image separate from a main imagedisplayed on a screen will be referred to as a 3D object or a 3D imageobject. The 3D object may include subtitles, captions, logos, additionalmenus, etc. provided in addition to the main image of the screen, as anembodiment. That is, a broadcast receiver may receive data for the 3Dobject and add the data to the main image, thereby displaying the dataand image. In this case, the 3D object data received by the broadcastreceiver may include caption/graphical data for the 3D object anddisparity information for a 3D effect.

FIG. 1 is a diagram illustrating a 3D object display method according toan embodiment of the present invention;

In FIG. 1, a left display image 1010 represents a video planecorresponding to a left view and a right display image 1020 represents avideo plane corresponding to a right view. In FIG. 1, a 3D objectcorresponds to caption texts 1030 and 1040. In case of a stereoscopicimage display scheme, both an image corresponding to the left view andan image corresponding to the right view are displayed on one screen. Aviewer views the left view image and the right view image through theleft eye and the right eye of 3D glasses, respectively. In this case,the left view image and the right view image are displayed apart fromeach other by a predetermined interval as shown in FIG. 1 and thisinterval may be referred to as a disparity value.

3D object data may include data about the object (e.g. images, textinformation, etc.) and information about a disparity value. Uponreceiving the 3D object data, a broadcast receiver may process dataabout an object to display the object as shown in FIG. 1 and may shiftan object of an extended view image by a disparity value to display a 3Dobject.

In FIG. 1, the left view 3D object 1030 and the right view 3D object1040 are displayed apart from each other by a predetermined disparityvalue. A viewer views the 3D object having a 3D effect corresponding toan interval of the disparity value.

FIG. 2 is a diagram illustrating a 3D effect of 3D object displayaccording to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a 3D effect of a 3D object when theleft view image and right view image of FIG. 1 are synthesized and thendisplayed. As shown in FIG. 1, if the 3D object of the left view imageand the 3D object of the right view image are displayed spaced apart byan interval of the disparity value, a 3D effect corresponding to thedisparity value appears.

In FIG. 2, a 3D object 2010 shows the case of displaying the 3D objectat an original display screen location without a 3D effect. A 3D object2020 shows the case of displaying the 3D object as if the 3D objectappears to move towards the viewer. A 3D object 2030 shows the case ofdisplaying the 3D object as if the 3D object appears to move furtherfrom the viewer.

In this case, the viewer recognizes the 3D object 2030, which appears tobe far away, as a bigger object than the 3D object 2020, which appearsto be close, according to a size constancy principle. In other words,when the viewer recognizes the size of an object, the distance betweenthe viewer and the object has an effect on recognition of the size ofthe object. Accordingly, if a 3D effect is assigned to objects havingthe same size, the size of an object is recognized as being big or smallin proportion to distance according to distance perception caused by the3D effect.

In an actual experiment using a 3D object such as 3D caption data or 3Dgraphics on a stereoscopic display, if distances are adjusted byassigning different disparity values to 3D objects of the same size, thesize of a 3D object appears relatively smaller as the 3D object protrudetowards a screen, i.e. as the 3D object is near to the viewer.

Thus, variation of the size of a 3D object recognized by a viewer isproportional to distance and, as a result, subtitle/graphic data may bedistorted during 3D image view. A method and apparatus which are capableof compensating such distortion are proposed below.

As described above, the broadcast receiver receives 3D object data whichincludes graphic data or image data for the 3D object and disparityinformation for producing a 3D effect. According to the presentinvention, a method is proposed for resizing a 3D object by calculatinga distortion compensation factor so as to compensate for a distortedsize caused by a 3D effect.

A disparity value included in the disparity information denotes adifference in distance between a left view image and a right view imageon a display screen and may typically be expressed as a pixel unit. Incontrast, a parallax value denotes a distance of an image focused on ascreen and may be expressed in inches or centimeters. Hereinafter, adescription will be given of the method for resizing a 3D object bycalculating the parallax value using the disparity value included in thereceived 3D object data and calculating a distortion compensation factorusing the calculated parallax value.

FIG. 3 is a diagram illustrating 3D object display in accordance with adisparity value according to an embodiment of the present invention.

If the left and right view images are displayed according to a disparityvalue as illustrated in FIG. 1 and FIG. 2, a 3D object viewed by aviewer is illustrated in FIG. 3.

In FIG. 3, an x-y plane corresponds to a screen when a disparity valueis 0. A video object 1 has a negative disparity value and has a 3Deffect as if the video object 1 appears to move towards the viewer fromthe screen. A video object 2 has a positive disparity value and has a 3Deffect as if the video object 2 appears to move further from the viewertowards the screen.

A broadcast receiver receives 3D object data and processes graphicdata/image data to express an object on the x-y plane. Next, thebroadcast receiver displays a 3D object so as to produce an effect onthe z axis according to a disparity value.

Namely, the aforementioned size distortion phenomenon occurs accordingto the effect on the z axis related to the disparity value. Therefore, adistortion compensation factor may be calculated using the disparityvalue.

FIG. 4 is a diagram illustrating an interval between a user, an image,and a screen during 3D image display according to an embodiment of thepresent invention.

Referring to FIG. 4, an interval between a 3D object and a user isdenoted by X, an interval between the user and a display screen isdenoted by K, and an interval between the 3D object and the displayscreen is denoted by D (=K−X).

Hereinbelow, the case in which the size of a 3D object is compensatedbased on a disparity value of 0 will be exemplarily described. Sincegraphic/image data included in 3D object data received by a broadcastreceiver is graphic/image data expressing an object image when adisparity value is 0 and a 3D object is displayed with distancesaccording to the disparity value, a compensation factor will becalculated based on the size of the 3D object when the disparity valueis 0.

First, the interval X between the 3D object and the user may berepresented by the following Equation 1:X=K*Id/(Id−p)  [Equation 1]

In Equation 1, K denotes a distance between a screen and user eyes, Iddenotes an interocular distance, and p denotes a parallax on the screen.

The parallax may be expressed using a disparity value and may berepresented by Equation 2 below:p=d*(16/sqrt(337))*S/vw  [Equation 2]

In Equation 2, p denotes a parallax value, d denotes a disparity value,S denotes a diagonal size of a screen, and vw denotes the width of acoded video.

Equation 2 represents a parallax using a disparity value when a screenratio is 16:9 in one an embodiment. When a disparity value is −50 on a47-inch Full High-Definition (HD) TV, a parallax value corresponds to−2.7 cm. In this case, if a user views an object on a screen from adistance of 5 m, a distance between the user and the object recognizedby the user corresponds to 3.53 m.

As indicated by Equation 3, a distortion compensation factor may becalculated using Equation 1 and Equation 2.

$\begin{matrix}\begin{matrix}{F = {K/X}} \\{= {\left( {{Id} - p} \right)/{Id}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

First, a distortion compensation factor F may be expressed as K/Xthrough which an optical illusion caused by the distance perception of a3D object is compensated. This distortion compensation factor F may beexpressed by (Id−p)/Id using Equation 1. In other words, the broadcastreceiver may obtain the distortion compensation factor using Equation 3which calculates a parallax value using disparity information includedin received 3D object data. The interocular distance Id may be a setaverage value or may be an interocular value input by a user.

The broadcast receiver may adjust display of a 3D object by adjustingthe original size of a 3D object image according to the distortioncompensation factor.

3D object data is included in a broadcast signal. In the embodiment ofthe present invention, a 3D object includes captions or subtitles. Ifthe 3D object corresponds to captions or subtitles, the 3D object datamay be received in video data of a broadcast signal or may be receivedthrough an additional Elementary Stream (ES). The above-described 3Dimage compensation method will be described below with respect to eachcase. Captions or subtitles will be exemplarily described as an exampleof the 3D object.

FIG. 5 is a diagram illustrating a broadcast receiver according to anembodiment of the present invention.

The broadcast receiver of FIG. 5 shows an embodiment of a broadcastreceiver for processing caption data received in a header region ofvideo data. As an embodiment, the broadcast receiver of FIG. 5 may be abroadcast receiver for receiving and processing a broadcast signal of anAdvanced Television System Committee (ATSC) system. Hereinafter, thecaption data may be referred to as DTV Closed Caption (DTVCC).

The broadcast receiver includes a tuner/demodulator 5010 for tuning anddemodulating a broadcast signal, a Vestigial Side Band (VSB) decoder5020 for decoding a VSB for a received broadcast signal and generating abroadcast stream, a Transport stream (TP) demultiplexer 5030 fordemultiplexing the broadcast stream to generate a Program and SystemInformation Protocol (PSIP) data ES, a video ES, etc., a PSIP processor5040 for processing PSIP data to obtain system information, a videodecoder 5050 for decoding video data included in a 3D video ES, a DTVCCdecoder 5060 for receiving and decoding DTVCC data from the videodecoder, a graphics engine 5070 for performing scaling with respect to adecoded caption in consideration of disparity/depth, an On ScreenDisplay (OSD) processor 5080 for OSD-processing a scaled caption, and aformatter 5090 for output-formatting a main video and an OSD screen. Thetuner/demodulator 5010 and the VSB decoder 5020 are collectivelyreferred to as a broadcast signal receiver. The graphics engine may bereferred to as a 3D graphics processor. Each of the video decoder andthe DTVCC decoder may be referred to as a decoder.

The broadcast receiver of FIG. 5 receives and demodulates a broadcastsignal including 3D broadcast data through the tuner/demodulator. Thebroadcast signal includes 3D video data, audio data, and additionaldata. DTVCC (caption) data may be included in a picture user data partof a header region of the video data. The broadcast receiver of 3D videoVSB-decodes the received broadcast signal through the VSB decoder andgenerates the decoded signal as a Transport Stream (TS).

The TP multiplexer 5030 of the broadcast receiver outputs signalinginformation included in the broadcast signal to the PSIP processor 5040.The PSIP processor 5040 determines a Packet Identifier (PID) of a videoES using the signaling information. The signaling information representsPSI/PSIP information. The PSIP information may include information abouta Program Map Table (PMT), a Virtual Channel Table (VCT), and EventInformation Table (EIT).

The broadcast receiver performs PID filtering through the TPdemultiplexer 5030 to output 3D video data to the video decoder 5050.The video decoder 5050 decodes the 3D video data and outputs DTVCC dataincluded in a header of the 3D video data (e.g. a header and extensionregion of MPEG2 video data) to the DTVCC decoder 5060.

The DTVCC decoder 5060 decodes DTVCC data. The DTVCC data may include atleast one of caption data, viewpoint information, and disparity/depthinformation. The caption data includes image or text data for a captionto be output and information about an output location (coordinateinformation).

The broadcast receiver processes the caption data using the graphicsengine 5070. First, the broadcast receiver determines caption outputcoordinates on a left/right video plane using the disparity informationincluded in the DTVCC data. The broadcast receiver calculates a parallaxwhich is a distance between caption data on a video screen from adisparity using the above Equation 1 to Equation 3 in consideration ofthe size of the video screen, video resolution, etc. For example, incase of a caption output on a full HD screen video on a 47-inch 3D TV, aparallax value corresponding to a disparity of −50 pixels is −2.7 cm. Ifthe parallax value is calculated, a distortion compensation factor canbe calculated using the parallax value and an interocular distance byEquation 3. In case of adults, the interocular distance may use 6.5 cmas a basic value or may use a value input by a user.

The broadcast receiver adjusts the size of a caption to be finallyoutput using the calculated distortion compensation factor. The size ofthe caption may be adjusted by multiplying a font size or image size ofthe caption by the distorting compensation factor. That is, the size ofthe finally displayed caption is adjusted in proportion to distancessuch that the caption in the forward direction of a screen becomessmaller and the caption in the backward direction of the screen becomeslarger.

FIG. 6 is a diagram illustrating a broadcast receiver according toanother embodiment of the present invention.

Unlike the broadcast receiver of FIG. 5, the broadcast receiver of FIG.6 shows an embodiment of a broadcast receiver for processing captiondata when the caption data is received in a separate stream. In theembodiment of FIG. 6, the caption data may be referred to as subtitledata. As an embodiment, the broadcast receiver of FIG. 6 may be abroadcast receiver for receiving and processing a broadcasting signal ofa Digital Video Broadcasting (DVB) system.

The subtitle data includes subtitle data for a base view and subtitledata for an extended view. The subtitle for the base view includesdisplay definition information for display window configurationnecessary for displaying the subtitle, page composition information,region composition information, and object data information which may bereferred to as a Display Definition Segment (DDS), a Page CompositionSegment (PCS), a Region Composition Segment (RCS), and an Object DataSegment (ODS), respectively, in a syntax structural meaning duringtransmission. The subtitle data for the extended view may be referred toas extended subtitle data for 3D display and may include DDS_EXT,PCS_EXT, RCS_EXT, and ODS_EXT as in the subtitle data for the base view.Disparity information or depth information for 3D display may beincluded in at least one of the subtitle data for the base view and thesubtitle data for the extended view. The extended subtitle data mayinclude information about subtitle output locations or coordinates anddisparity information.

The broadcast receiver of FIG. 6 includes a broadcast signal receiver(not shown) for receiving and demodulating a broadcast signal togenerate a broadcast stream, a demultiplexer 6010 for extractingsubtitle data using a PID corresponding to subtitle data from thebroadcast stream, a section filter 6020 for filtering the subtitle dataaccording to each section, an Extended View (EV) subtitle decoder 6030for decoding subtitle data for an extended view, a Base View (BV)subtitle decoder 6040 for decoding subtitle data for a base view, acomposition buffer 6050 for buffering data according to each section, anEV pixel buffer 6060 for buffering the subtitle data for the extendedview, a BV pixel buffer for buffering the subtitle for the base view, a3D graphic processor 6080 for receiving data from each buffer, readingand processing the data, and displaying 3D subtitles, and a Color LookUp Table (CLUT) processor 6090 for processing a CLUT Definition Segment(CLUTDS). Hereinafter, each of the EV subtitle decoder 6030 and the BVsubtitle decoder 6040 may be referred to as a decoder, and each of theEV pixel buffer 6060 and the BV pixel buffer 6070 may be referred to asa pixel buffer. The 3D graphics processor 6080 may be referred to as agraphics engine.

The broadcast receiver determines a PID for video data and subtitle datausing signaling information (PMT etc.). As an embodiment, DVB subtitledata may have a PID of a stream, a type value of the stream being 0x06.

The broadcast receiver divides a broadcast stream into a video streamand a subtitle stream (data) through the demultiplexer 6010 and outputsthe streams to the decoder. The broadcast receiver extracts subtitledata using data_identifier information and subtitle_stream_idinformation included in a PES_packet_data_byte region from a stream(e.g. Packetized Elementary Stream (PES)) corresponding to the subtitledata through the section filter 6020 and may generate the subtitle dataaccording to each section in consideration of segment_type information.

The broadcast receiver decodes the subtitle data through the decoders6030 and 6040. The 3D graphics processor 6080 processes the decodedsubtitle data and generates a 3D subtitle. Like the above-describedcaption data, the subtitle data includes image or text information forthe subtitle, subtitle output location or coordinate information, anddisparity or depth information for a 3D effect.

Operation of the 3D graphics processor 6080 is similar to operation ofthe graphics engine described with reference to FIG. 5 and will bedescribed below.

The broadcast receiver determines output coordinates of subtitle graphicdata on a video plane of a left/right view (base view and extended view)using disparity information through the 3D graphics processor 6080. Thebroadcast receiver calculates a parallax which is a distance betweencaption data on a video screen from the disparity information using theabove Equation 1 to Equation 3 in consideration of the size of the videoscreen, video resolution, etc. For example, in case of a caption outputon a full HD screen video on a 47-inch 3D TV, a parallax valuecorresponding to a disparity of −50 pixels is −2.7 cm. If the parallaxvalue is calculated, a distortion compensation factor can be calculatedusing the parallax value and an interocular distance by Equation 3. Incase of adults, the interocular distance may be 6.5 cm as a basic valueor may be a value input by a user.

The broadcast receiver adjusts the size of a caption to be finallyoutput using the calculated distortion compensation factor. The size ofthe caption may be adjusted by multiplying a font size or image size ofthe caption by the distortion compensation factor. That is, the size ofthe finally displayed caption is adjusted in proportion to distancessuch that the caption in the forward direction of a screen becomessmaller and the caption in the backward direction of the screen becomeslarger.

FIG. 7 is a flowchart illustrating a 3D object display method accordingto an embodiment of the present invention.

The 3D object display method of FIG. 7 shows a 3D object display methodperformed in the broadcast receiver shown and described in FIG. 5 andFIG. 6.

The broadcast receiver demodulates a broadcast signal including 3Dobject data using the broadcast signal receiver (S7010). A 3D objectrepresents an image other than a main video, for example, captions,subtitles, menus, and logos provided to a user. In case of captions andsubtitles, the 3D object data may be included in a header region ofvideo data or may be received through a separate ES, as describedpreviously.

The broadcast receiver decodes the 3D object data using the decoder(S7020). The 3D object data includes image information about at leastone of text, graphics, and moving pictures for the 3D object, locationinformation about a location on a screen at which the 3D object is to bedisplayed, and disparity or depth information necessary for producing a3D effect. The location information may include coordinate informationfor locations at which the 3D object is positioned on the screen.

The broadcast receiver calculates a distortion compensation factor forcompensating size distortion according to 3D display of the 3D objectthrough the graphics engine or 3D graphics processor (S7030). In moredetail, if disparity information is included in the 3D object data, thebroadcast receiver calculates a parallax value from a disparity valueusing the above equations. A distortion compensation factor may becalculated from the parallax value and an interocular distance throughthe above equations. The interocular distance may be a preset defaultvalue (e.g. 6.5 cm) or may be another value according to race, sex, andage of a user. The interocular distance input by a user may also beused.

If depth information is included in the 3D object data, the distortioncompensation factor may be calculated directly using the depthinformation. In the distortion compensation factor F=K/X of Equation 3,K denotes a distance between a screen and a viewer and X denotes a valueobtained by converting a depth value D into a physical distance. Thatis, if the depth value is defined as a value between 0 and 255, thephysical value X perceived by a viewer during display on an actual 3Dscreen with respect to those values is present. The broadcast receivermay calculate depth coded to an image as a distance perceived by aviewer or may acquire the value X using depth mapping informationobtained by mapping the depth to a physical distance, thereby directlycalculating the distortion compensation factor using the value X. Inother words, the distortion compensation factor F may be calculated byF=K/X=K/(K−D) where D denotes a physical distance value obtained bymapping the depth value to a distance between a screen and a 3D object.Nonetheless, a preset value or a value input by a user may be used asthe distance between the screen and the viewer.

The broadcast receiver adjusts the size of the 3D object using thedistortion compensation factor through the graphics engine or 3Dgraphics processor (S7040). The size of the 3D object may be adjusted bymultiplying the distortion compensation factor by the font or image sizeof the caption. Namely, the size of the 3D object is adjusted bymultiplying the distortion compensation factor by a font size or thewidth/length size of the image. The finally displayed 3D object isoutput such that the caption in the forward direction of a screenbecomes smaller and the caption in the backward direction of the screenbecomes larger.

Finally, the broadcast receiver outputs the size-adjusted 3D object(S7050).

The size of the 3D object is automatically adjusted. However, the sizeof the 3D object may be adjusted according to user selection. That is, aUser Interface (UI) which is capable of adjusting the size of the 3Dobject according to user input is displayed and the size of the 3Dobject can be adjusted according to user selection. When a userincreases or decreases the size of the 3D object, the size of the 3Dobject may be adjusted by receiving a size variation corresponding tothe increased or decreased size and reflecting the size variation in thedistortion compensation factor.

FIG. 8 is a diagram illustrating a UI for adjusting the size of a 3Dobject according to an embodiment of the present invention.

In FIG. 8, a caption is illustrated as the 3D object.

The broadcast receiver may display a UI for changing the size of acaption, such as a screen 8010. The UI may be activated by user input ormay be automatically activated when the caption is displayed.

If a user selects a size change through input means such as a remotecontroller (the case in which the user selects ‘YES’ through the UI ofthe screen 8010), the broadcast receiver may display the UI of a screen8020. The user may adjust the size of the caption by shifting an arrowas indicated by dotted lines through user input means.

If the size of the caption is input, the broadcast receiver may adjustthe size of the caption by performing steps after step S7030 in FIG. 7.In other words, the step of receiving the adjustment of the caption sizefrom a user by displaying the UI of the 3D object may be performedbetween steps S7020 and S7030 or between steps S7030 and S7040.

MODE FOR INVENTION

As described previously, various embodiments have been described in thebest mode for carrying out the invention.

INDUSTRIAL APPLICABILITY

As described above, the present invention may be totally or partiallyapplied to a digital broadcasting system.

The invention claimed is:
 1. A method of processing 3D broadcast data,comprising: receiving a broadcast signal including signalinginformation, video data and 3D object data; decoding the 3D object data,wherein the 3D object data includes data about a 3D object, wherein thebroadcast signal includes disparity information of the 3D object;acquiring a parallax value from the disparity information andcalculating a distortion compensation factor using the parallax value,wherein the distortion compensation factor is calculated by thedistortion compensation factor=(an interocular distance value−theparallax value)/an interocular distance value; adjusting a display sizeof the 3D object by multiplying the display size of the 3D object by thecalculated distortion compensation factor; and displaying the 3D objecthaving the adjusted display size.
 2. The method of claim 1, wherein thedata about the 3D object includes at least one of image information andtext information.
 3. The method of claim 1, wherein the 3D object dataincludes at least one of output location information of the 3D objectand depth information of the 3D object.
 4. The method of claim 1,wherein the 3D object data includes caption data and the 3D object datais included in a header part of the video data.
 5. The method of claim1, wherein the 3D object data includes subtitle data and the 3D objectdata is received through an Elementary Stream (ES) separate from thevideo data.
 6. The method of claim 3, wherein the distortioncompensation factor is calculated by using the depth information.
 7. Anapparatus of processing 3D broadcast data, comprising: a receiver forreceiving a broadcast signal including signaling information, video dataand 3D object data; a decoder for decoding the 3D object data, whereinthe 3D object data includes data about a 3D object, wherein thebroadcast signal includes disparity information of the 3D object; agraphics engine for acquiring a parallax value from the disparityinformation, calculating a distortion compensation factor using theparallax value, and adjusting a display size of the 3D object bymultiplying the display size of the 3D object by the calculateddistortion compensation factor, wherein the distortion compensationfactor is calculated by the distortion compensation factor=(aninterocular distance value−the parallax value)/an interocular distancevalue; and a formatter for displaying the 3D object having the adjusteddisplay size.
 8. The apparatus of claim 7, wherein the data about the 3Dobject includes at least one of image information and text information.9. The apparatus of claim 7, wherein the 3D object data includes atleast one of output location information of the 3D object and depthinformation of the 3D object.
 10. The apparatus of claim 7, wherein the3D object data includes caption data and the 3D object data is includedin a header part of the video data.
 11. The apparatus of claim 7,wherein the 3D object data includes subtitle data and the 3D object datais received through an Elementary Stream (ES) separate from the videodata.
 12. The apparatus of claim 9, wherein the distortion compensationfactor is calculated by using the depth information.